Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical elements and electronics on a common substrate, allowing the realization of a complete system on a single chip. MEMS resonators are passive elements that possess a high quality factor (Q) and that can be used to integrate filtering, oscillator, and other functions on a single chip for applications such as wireless communications systems. As an example, MEMS resonators can advantageously be used at intermediate frequency (IF) and radio frequency (RF) in communications systems based on superheterodyne, quasi-direct conversion, and direct conversion architectures. A MEMS resonator can replace discrete elements, active circuitry, and/or inductor-capacitor (LC) resonators and provide the same functionality with a higher Q, lower power consumption, lower noise, and lower parts count, thus enabling systems with higher performance at lower cost. In existing MEMS resonators, however, the electromechanical coupling decreases as the frequency of the resonator increases, meaning such resonators are increasingly harder to drive at higher frequencies. Accordingly, a need exists for a resonator in which the electromechanical coupling is independent of the resonator frequency.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly connected in an electrical or non-electrical manner.